Re: Why does not rgrep use "grep -r"?

["Lennart Borgman (gmail)" <lennart.borgman@gmail.com>]

Kim F. Storm wrote:
> Miles Bader <miles@gnu.org> writes:
> 
>> "Lennart Borgman (gmail)" <lennart.borgman@gmail.com> writes:
>>> If grep can do recursive searches then why not use that in rgrep?
>> I don't know the reason of the rgrep authors (though I suspect it was
>> portability concerns), 
> 
> Yes portability was definitely a concern.
> 
> When I first wrote the code years ago, grep -r wasn't widely supported,
> so I wrote it to use find, xargs, and grep.
> 
> Later when I integrated rgrep into Emacs 22.1, I reworked quite a lot
> of the existing grep & find stuff so that the old grep and grep-find, and
> the new lgrep and rgrep commands could share a common code base.
> 
> Since both grep-find and my rgrep code used find/xargs/grep, I decided
> to continue using them, even though grep -r could have been an alternative.
> 
> But I was still concerned about portability, and since using find
> worked just nicely, I saw no reason to change.  Besides, as you and
> others have noted, grep -r has severe performance problems on some
> platforms.
> 
> It probably wouldn't be difficult to make it used grep -r (as an
> _optional alternative_), but the current code works nicely and is well
> tested, so why mess with it?

I thought performance was one reason, but maybe not.

However there are other problems, at least on w32. Try a search with a 
space in it. That works with lgrep, but not with rgrep. -- At least that 
is true when you are using the utilities from GnuWin32.

So I suggest that the default on w32 is changed to use grep -r.